Seventeen people have been killed in two separate attacks in a province of north-eastern Iraq which was once an al-Qa'ida stronghold, officials said today.

The marketplace car bombing and the assault on the home of an anti-al-Qa'ida militia leader came on the third day of a visit by US Vice President Joe Biden, in advance of the withdrawal of American troops at the end of the year.

A parked car bomb exploded in the town of Khalis as morning shoppers were starting to arrive, killing 10 people and injuring 22 others, two police officials said.

Khalis, a Shiite enclave 50 miles north of Baghdad, is surrounded by the largely Sunni province of Diyala. The province was a hotbed of al-Qa'ida in Iraq during the height of the country's violence in 2004-2007.

Also in Diyala, gunmen stormed the home of an anti-al-Qa'ida Sunni fighter at dawn and killed seven people, police said.

The victims of the attack in the town of Buhriz, about 35 miles north of Baghdad, included the local leader of the pro-government Sahwa or Awakening Councils movement and six members of his family, four of whom were women.

Faris al-Azawi, the spokesman for Diyala's health directorate, confirmed the death tolls in both Khalis and Buhriz.

The attacks came as Mr Biden met Iraqi officials during a trip designed to chart a new relationship between the two countries ahead of the withdrawal of US forces by the end of this year.

Iraqi security officials maintain that they are fully prepared for the American withdrawal, which is required under a 2008 security pact between the US and Iraq.

About 13,000 US troops are still in the country, down from a one-time high of about 170,000. All of those troops will be out of the country by the end of December.

But many Iraqis are concerned that insurgents may use the transition period to launch more attacks in a bid to regain their former prominence and destabilise the country.

At least 56 Iraqis have been killed in separate attacks across the country in the past eight days, a warning that even more violence may be in the offing ahead of the American withdrawal.

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